1. Field of the Invention
The present invention relates to a device for supplying a gas-air mixture to burners in heating apparatuses, comprising: a ventilation unit provided with a fan wheel operatively engaged in a fixed box-shaped portion having an inlet opening communicating with the external environment and an outlet opening to be connected with a burner, a gas-supplying valve unit comprising drive means operating on at least one valve seat to selectively open the gas passage through the valve seat itself, a mixing duct bringing the valve unit into fluid communication with the ventilation unit.
In particular the device in question is such conceived as to be advantageously utilized in heat-supplying boilers for household use. However application of the invention to heating apparatuses of different kinds may be provided.
2. Prior Art
It is known that heating apparatuses for household use such as boilers, water heaters and the like generally comprise a burner at the outlet opening of which an air-gas mixture fed through the burner itself is fired to produce the necessary heat for heating the water contained in appropriate accumulators and/or heat exchangers.
In apparatuses equipped with a burner of the pre-mixed type, the air-gas mixture is formed upstream of the burner, by cooperation between an air-feeding unit generally consisting of a centrifugal fan, and a gas-supplying valve unit. The ventilation and gas-supplying units are mutually interconnected by a connecting duct that, depending on the applications, can be located upstream or downstream of the ventilation unit and they are driven by an electronic control unit managing operation thereof depending on the requirements dictated by different operating parameters suitably controlled by the electronic control unit itself.
All that being stated, it is to point out that presently the ventilation unit and gas-supplying valve unit, as well as the electronic control unit, are accomplished as units completely distinct from each other, each of which is installed in a specific space expressly arranged for it within the holding structure of the boiler or other heating apparatus. This solution has been always deemed capable of offering a good project freedom to the heating apparatus manufactures, due to the possibility of managing the individual modules in an independent manner in the available spaces within the apparatuses themselves. However, it has now been realized that while managing of the ventilation unit, gas-supplying unit and control unit as distinct and separated modules appears to be advantageous under the point of view of freedom in planning, it actually brings about different drawbacks, among which stock managing of the individual modules is of great importance.
Difficulties are also encountered by the heating apparatus manufacturers in carrying out the planning management of the separated modules. These difficulties are further increased by the fact that, in most cases, the ventilation, gas-supplying and control units employed on a given apparatus do not come from one and the same manufacturer, but from different manufacturers, each skilled in a specific field. The heating apparatus designer therefore, must exactly know all operating parameters of each individual unit in order to verify and ensure the perfect compatibility between the different modular units even when subsequent adaptations are carried out.
It is also to point out that the fact itself that the units are accomplished as distinct and separate modules involves an increase in the overall production costs.